Activation of NO2 by Modifying the Porphyrin Unit with Oxygen in a MnN4 Graphene Layer

In this article, the activation of N−O bonds in NO2 molecules has been investigated by Density Functional Theory (DFT) calculations. Considering the graphene-based MnN4 layer, nitrogen atoms in the porphyrin unit were sequentially replaced with oxygen atoms to create different MnNmOn/G (m+n=4 and 1<m≤4) layers. As more oxygen atoms are incorporated in porphyrin units for bare layers, the covalent character of the Mn−O bonds is switched to the transit nature with respect to Mn−N bonds. Moreover, the trend in bond strength decreasing in all oxygen-containing bonds is in line with the formation energy trends of bare layers. The same situation is also valid for the bonds between Mn−N/O. For NO2 adsorption configurations on all MnNmOn/G layers, N−O bonds in NO2 are weakened by populating/depopulating antibonding/bonding orbitals, respectively. Even if the MnN2O2(hex)/G layer has a moderate NO2 adsorption energy among the other layers, this layer provided the most significant activation over N−O bonds based on crystal orbital Hamilton population (COHP), crystal orbital bond index (COBI), and Atoms in Molecules (AIM) Bader Topological Analysis. Our results show that integrated COHP and integrated COBI values show a remarkable correlation with AIM-Bader parameters for the specific bonds which have descriptive capability over NO2 molecule activation

Characteristic Features of Children with Neurofibromatosis Type 1

Neurofibromatosis Type 1 (NF-1) is the most common, progressive, multisystemic, autosomal dominant neurocutaneous syndrome. Its clinical features begin to present during childhood. Early diagnosis and follow-up of children with NF-1 is necessary due to predisposition to tumors and complications. Herein we aimed to evaluate patient characteristics', neuroradiologic findings and frequency of tumors in children with NF-1 who have been followed up at our center from January 1989 to June 2008. Medical records of 64 children with NF-1 were analized retrospectively for age, gender, diagnostic criteria for NF-1, unidentified bright objects (UBOs) on magnetic resonance imaging (MRI), complications related to NF-1, and tumors. The median age of patients was 9.5 years (0.5 18), M:F ratio was 1.2. The incidence of the diagnostic criteria were as following, café au lait spots: 100%, freckling: 62.5%,neurofibromas ± plexiform neurofibromas: 47%, Lisch nodules: 38%, optic gliomas: 11%,distinctive osseous lesions: 11%, and first degree relative with NF- 1: 30%. Cranial MRI had been performed in 38 patients, and 58% of them revealed UBOs. The most common complications were kyphoscoliosis (19%), convulsion (11%). Benign tumors and malignant ± benign tumors developed in52%and19%of patients, respectively. The importance of careful physical examination was showed by the high frequency of positive clinical diagnostic criteria of NF-1. The frequency of UBOs on MRI was high in children with NF-1. This was suggested that neuroradiologic findings may be proposed as an additional diagnostic criterion for NF-1, particularly for young children who didn't meet the diagnostic criteria. Management and follow up of complications related to NF-1, and offering genetic counseling to parents could be making by early diagnosis of NF-1 in childhood. The predisposition to tumors and the high frequencies of complications related to NF-1 were showed that the importance of multidisciplinary follow up of children with NF-1.Nörofibromatozis Tip1 (NF1) toplumda en sık karsılasılan, klinik bulguları çocukluk çagında ortaya çıkmaya baslayan, zamanla ilerleyici seyir göstererek pek çok sistemi etkileyebilen otozomal dominant geçisli bir nörokutan sendromdur. Beniyn ve maliyn tümör gelismesine yatkınlık yaratması ve NF1 iliskili komplikasyonlar nedeniyle, NF1' in çocukluk çagında erken tanısı ve klinik izlemi önemlidir. Bu çalısmada merkezimizde Ocak 1989-Haziran 2008 tarihleri arasında, NF1 tanısıyla izlenen çocuk hastaların karakteristik özellikleri, nöroradyolojik bulguları ve tümör sıklıgınındegerlendirilmesi amaçlanmıstır. Nörofibromatozis Tip1 tanı kriterlerini karsılayan 64 hastanın dosyaları retrospektif olarak incelendi. Hastaların yas, cinsiyet, NF1 tanı kriterleri, manyetik rezonans görüntülemede (MRG) tanımlanmamıs parlak objelerin (UBO: unidentified bright objects) görülme sıklıgı, NF1 iliskili komplikasyonlar, gelisen tümörler degerlendirildi. Hastaların ortanca tanı yası 9.5 yas (0.5 18), E:K oranı 1.2 bulundu. Tanı kriterlerinin sıklıgı: sütlü kahve lekeleri %100, çillenme %62.5, nörofibrom veya pleksiform nörofibrom %47, Lisch nodülü %38, optik gliom %11, kemik lezyonu %11, birinci derece akrabalarda NF1 tanısı %30 bulundu. Kraniyal MRG yapılan 38 hastadan 58%'inde UBO mevcuttu. En sık gelisen komplikasyonlar; kifoskolyoz (%19) ve konvülzyondu (%11). Hastaların %52'inde beniyn, %19'inde maliyn±beniyn tümörler gelismisti. Nörofibromatozis Tip1'in fizik inceleme ile saptanabilen klinik tanısal kriterlerinin sıklıgı, iyi bir fizik incelemenin önemini göstermektedir. Kraniyal MRG ile NF1 tanılı çocuk hastalarda yüksek oranda UBO pozitifligi izlendigi görülmüstür. Bu bulgu, özellikle henüz klinik bulguları NF1 kriterlerini karsılamayan küçük yas grubunda nöroradyolojik bulguların ek bir kriter olarak arastırılmasının hastaların erken tanısını saglayabilecegini düsündürmektedir. Erken tanı ile hem çocukta gelisebilecek problemlerin izlemi ve tedavisi, hem de ailelere genetik danısma verilmesi saglanabilecektir. Beniyn ve maliyn tümörlere yatkınlık ve diger NF1 iliskili komplikasyonların sıklıgının yüksek olması, NF1 tanılı çocukların multidisipliner izleminin önemini göstermistir

Prognostic factors for regorafenib treatment in patients with refractory metastatic colorectal cancer: A real-life retrospective multi-center study

Regorafenib, an oral multikinase inhibitor, has improved survival in metastatic colorectal cancer (mCRC) patients who have progressed on standard therapies. Our study aimed to evaluate prognostic factors influencing regorafenib treatment and assess the optimal dosing regimen in a real-life setting. We retrospectively analysed 263 patients with mCRC from multiple medical oncology clinics in Turkey. Treatment responses and prognostic factors for survival were evaluated using univariate and multivariate analysis. Of the patients, 120 were male, and 143 were female; 28.9% of tumors were located in the rectum. RAS mutations were present in 3.0% of tumors, while BRAF, K-RAS, and N-RAS mutations were found in 3.0%, 29.7%, and 25.9% of tumor tissues, respectively. Dose escalation was preferred in 105 (39.9%) patients. The median treatment duration was 3.0 months, with an objective response rate (ORR) of 4.9%. Grade ≥ 3 treatment-related toxicity occurred in 133 patients, leading to discontinuation, interruption, and modification rates of 50.6%, 43.7%, and 79.0%, respectively. Median progression-free survival (PFS) and overall survival (OS) were 3.0 and 8.1 months, respectively. RAS/RAF mutation (hazard ratio [HR] 1.5, 95% confidence interval [CI] 1.1-2.3; P = 0.01), pretreatment carcinoembryonic antigen (CEA) levels (HR 1.6, 95% CI 1.1-2.3; P = 0.008), and toxicity-related treatment interruption or dose adjustment (HR 1.6, 95% CI 1.1-2.4; P = 0.01) were identified as independent prognostic factors for PFS. Dose escalation had no significant effect on PFS but was associated with improved OS (P < 0.001). Independent prognostic factors for OS were the initial TNM stage (HR 1.3, 95% CI 1.0-1.9; P = 0.04) and dose interruption/adjustment (HR 0.4, 95% CI 0.2-0.9; P = 0.03). Our findings demonstrate the efficacy and safety of regorafenib. Treatment line influences the response, with dose escalation being more favorable than adjustment or interruption, thus impacting survival

OTOMOTİV SEKTÖRÜNDE KULLANILAN AZ91 MAGNEZYUM ALAŞIMININ KOROZYON DAYANIMINA ARK PVD SERAMİK FİLM KAPLAMALARIN ETKİSİ

Günümüz otomotiv sektörü, daha az yakıt sarfiyatı ve düşük gaz emisyonunun sağlanması için magnezyum (Mg) gibi hafif ve kolay şekillendirilebilen malzemelerin kullanılmasına yoğunlaşmıştır. Yapılan araştırmada, bu alaşımların düşük korozyon dayanımına sahip olduğu ve ilave kaplama yöntemleri ile geliştirilmesi gerektiği sonucuna varılmıştır. Bu bağlamda, çalışmada otomotiv sektörü malzemesi olan AZ91 Mg alaşımı Ark PVD yöntemi ile farklı parametreler kullanılarak TiN, AlTiN ve ZrN kaplanmış ve kaplamaların korozyon dayanımına etkisi deneysel olarak belirlenmiştir. Sonuç olarak, bu seramik film kaplamaların AZ91 Mg alaşımının korozyon dayanımını ciddi bir şekilde arttırdığı ve ortalama olarak AlTiN kaplı AZ91 Mg alaşımının en yüksek korozyon dayanımına sahip olduğu, bunu sırasıyla TiN ve ZrN kaplamalı AZ91 Mg alaşımları takip etmektedir

Hydrazine decomposition on nickel-embedded graphene

*Akça, Aykan ( Aksaray, Yazar )In this article, the catalytic effect of the Ni-embedded graphene has been investigated for hydrazine (N2H4) decomposition reaction through Density Functional Theory (DFT) calculations with Grimme-D2 dispersion correction. Nickel embedded graphene systems are expected to be much cheaper than pristine nickel surfaces in the future because of relatively few numbers of Ni atom usage, experimentally synthesizable, and limit the Ni usage. The transformation of N2H4 has been taken into account in two different ways. The first way is sequential N–H and, the second one is the N–N bond cleavage from the gauche conformation which is the most stable conformation in gas phase and sole conformation observed on the Ni site. According to our findings, ·NH2 formation breaking the N–N bond in hydrazine has lower activation energy than hydrogen abstraction from hydrazine. The difficulty of breaking N–H bonds stems from the spatial accumulation of negative and positive charges, so it causes a mismatch between hydrogen atoms and negatively charges carbon atoms. NH3 formation pathway through the interaction of N2Hx (x = 1 → 4) species with co-adsorbed ·NH2 radicals is accompanied by much lower activation barriers and highly exothermic. Nevertheless, metal-embedded graphene systems are promising materials for hydrazine dehydrogenation and can be tailored to have more efficient charge distributio

Ferhunde Erkin’in hayatı ve Türk müziğindeki yeri

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2015.This work is a student project of the The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.by Öztürk, İbrahim Mert

Ammonia free catalytic reduction of nitric oxide on Ni-embedded graphene nanostructure: A density functional theory investigation

In this study, the catalytic reduction reaction of NO (directly) without the presence of ammonia (NH3) was studied on the Ni-embedded graphene (Ni@GN) layer using periodic Density Functional Theory (DFT) calculations. Ni-embedded graphene surface can be synthesized experimentally and it is predicted that it will cost much less than single crystal surfaces due to the economic usage of the transition metal atoms. First of all, by optimizing the geometric structure of the Ni@GN layer, crucial geometric features and electron density differences (EDD) were obtained. Based on the different adsorption configurations of NO molecule, the reduction reaction was investigated by Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) based mechanisms. Finally, N2O degradation was analyzed in detail. It is shown that the Eley-Rideal model is a more dominant mechanism on the Ni@GN surface than the other model. In addition, all proposed reaction pathways for NO reduction are exothermic. This information can be used for the research and development of graphene-based materials for NO reduction; paves the way for finding new Ni-based catalysts based on active single transition metal atom embedded on different kind of defects

Veno-occlusive disease in a child with rhabdomyosarcoma after conventional chemotherapy: Report of a case and review of the literature

Although veno-occlusive disease of the liver is a well-known complication of high-dose chemotherapy and bone marrow transplantation, it has rarely been observed in children who receive conventional chemotherapy. Most cases in the literature consists of children with Wilms tumor. It has been very uncommon in rabdomyosarcoma patients until recently, although they commonly receive similar anticancer agents. Here the authors report a 2-year-old boy with rhabdomyosarcoma who developed veno-occlusive disease while receiving VAC (vincristine, actinomycin D, cyclophosphamide) chemotherapy regimen according to the IRS-IV protocol. The patient gradually recovered during 2 weeks with supportive treatment only

A pilot study evaluating the safety and toxicity of epirubicin, cisplatin, and UFT (ECU regimen) in advanced gastric carcinoma

Background: Best response rates have been achieved with three-drug regimens containing 5-FU in the treatment of advanced gastric cancer (AGC) and oral fluoropyrimidines are the best alternatives as substitutes for infusional 5-FU. This study aimed to evaluate the safety and toxicity of epirubicin, cisplatin, and UFT (ECU regimen) regimens in AGC outpatients